FIELD CROPS. 737 



In some instances 2 yellow colors appeared in the endosperm each behaving 

 when crossed with its absence as an independent allelomorphic pair. Both of 

 these colors, although they behave in inheritance as separate entities, are either 

 identical or very similar in composition. Data given show that in various 

 crosses between varieties with white and yellow endosperm yellow was domi- 

 nant and appeared as Xenia in the Fi kernels. The F- kernels in their cross 

 gave approximately the 3:1 (monohybrid) ratio. The F3 kernels all showed 

 the 3:1 ratio except one which showed the 15:1 (dihybrid) ratio. Dihybrid 

 ratios were also secured in several other crosses. The F2 seeds from the cross 

 between a White Flour corn and a Yellow Dent made it evident that this com- 

 bination was wholly monohybrid. having the 3:1 ratio. Among dihybrids the 

 extracted dominants In the Ft generations have in eveiy case bred true. 



The inheritance of the purple character was found to include also that of a 

 hypostatic red color which appears in the crosses between the various purple 

 and nonpurple families. The authors give exhaustive data on crosses between 

 purple and nonpurple varieties. The results all tend to show, as they state, 

 that the pui-ple aleurone color behaves as a normal Mendelian character in 

 inheritance. For exam])le, in the cross between a White Flint and Black Mexi- 

 can Sweet, the Fi kernels formed in the hybrid seeil were all purple. On gi'ow- 

 ing these seeds 9 selfed ears were obtained, 7 of which proved to be mono- 

 hybrid giving the 3:1 ratio, and 2 dihybrid giving a 1> : 7 ratio. In the F3 

 generation 1 of the above dihybrid ears was tested. Nineteen selfed ears were 

 obtained 2 of which were pure purple, 10 monohybrid, and 7 dihybrid. 



The authors formulate the following law in regard to Xenia : " When 2 races 

 differ in a single visible endosperm character in which dominance is complete. 

 Xenia occurs only when the dominant parent is the male ; when they differ in a 

 single endosperm character in which dominance is incomplete or in 2 charac- 

 ters both of which are necessary for the development of the visible difference, 

 Xenia occurs when either is the male." 



The authors iind in their studies of various plant characters that the jiodded 

 character of the podded maize is dominant and behaves as a simple Mendelian 

 monohybrid. Work carried on with regard to the factors which influence the 

 Llevelopmeut of the various red sap colors appearing in the pericarp, the cob, 

 the husks, the silks, the glumes, and the anthers shows that coupling sometimes 

 occurred, but as a rule iudeiiendent of the red in the other parts of the plant. 

 Simple monohybrid results were obtained. Data given show that the red cob 

 character is dominant to white cob and the red color in the silk to its absence. 



Abnormalities are generally found to segregate but no further conclusions 

 can yet be drawn on this point. 



An extensive bibliography is appended. 



Improvement in corn, H. K. Hayes and E. M. East (Connecticut 8tate Sta. 

 Bui. 16S, pp. 3-21, pis. //, figs. 1). — In this paper the authors discuss the dis- 

 advantages of the continued selection method of improving seed corn, and 

 show that even with every precaution to prevent it selection tends toward 

 inbreeding. Indian corn, as found in the field, consists of a number of types 

 which have been brought together in the different plants by cross fertilization. 

 Data are presented in tabular form which confirm this view and indicate that 

 in nearly all cases the first generation of inbreeding has the greatest detri- 

 mental effect, and " that after a type has been inbred until it is in a pure state, 

 continued inbreeding does not change its yielding ability." Inbreeding, there- 

 fore, has simply isolated the different types from the commercial variety. 



